This repository was archived by the owner on May 31, 2025. It is now read-only.
This repository was archived by the owner on May 31, 2025. It is now read-only.
Message hashes don't change with contents #73
Description
Eg:
$ python
Python 2.7.11 (default, Jan 22 2016, 08:29:18)
[GCC 4.2.1 Compatible Apple LLVM 7.0.2 (clang-700.1.81)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from std_msgs.msg import Int8
>>> foo = Int8()
>>> foo.data = 1
>>> hash(foo)
275653405
>>> foo.data = 2
>>> hash(foo)
275653405 # Should be different!
>>> bar = Int8()
>>> bar.data = 1
>>> hash(bar)
275876165 # Should be the same as the first one!
The default hash method supplied with object is based on identity rather than fields, hence the above behaviour.
Instead, generated messages should supply a __hash__ function which hashes the data, possibly as simple as just passing the message's string representation to hash.